Improve PCB flags handling and make it more robust. Add two new functions

for manipulating pcb_flags.  These inline functions are very similar to
atomic_set_char(9) and atomic_clear_char(9) but without unnecessary LOCK
prefix for SMP.  Add comments about the rationale[1].  Use these functions
wherever possible.  Although there are some places where it is not strictly
necessary (e.g., a PCB is copied to create a new PCB), it is done across
the board for sake of consistency.  Turn pcb_full_iret into a PCB flag as
it is safe now.  Move rarely used fields before pcb_flags and reduce size
of pcb_flags to one byte.  Fix some style(9) nits in pcb.h while I am in
the neighborhood.

Reviewed by:	kib
Submitted by:	kib[1]
MFC after:	2 months

2 files changed, 13 insertions, 12 deletions

diff --git a/sys/amd64/ia32/ia32_reg.c b/sys/amd64/ia32/ia32_reg.c
index da6eb0f..279df9a 100644
--- a/sys/amd64/ia32/ia32_reg.c
+++ b/sys/amd64/ia32/ia32_reg.c
@@ -125,7 +125,7 @@ set_regs32(struct thread *td, struct reg32 *regs)
 	tp->tf_fs = regs->r_fs;
 	tp->tf_es = regs->r_es;
 	tp->tf_ds = regs->r_ds;
-	td->td_pcb->pcb_full_iret = 1;
+	set_pcb_flags(pcb, PCB_FULL_IRET);
 	tp->tf_flags = TF_HASSEGS;
 	tp->tf_rdi = regs->r_edi;
 	tp->tf_rsi = regs->r_esi;
diff --git a/sys/amd64/ia32/ia32_signal.c b/sys/amd64/ia32/ia32_signal.c
index e0f30e2..808790b 100644
--- a/sys/amd64/ia32/ia32_signal.c
+++ b/sys/amd64/ia32/ia32_signal.c
@@ -130,8 +130,10 @@ ia32_set_fpcontext(struct thread *td, const struct ia32_mcontext *mcp)
 static int
 ia32_get_mcontext(struct thread *td, struct ia32_mcontext *mcp, int flags)
 {
+	struct pcb *pcb;
 	struct trapframe *tp;
 
+	pcb = td->td_pcb;
 	tp = td->td_frame;
 
 	PROC_LOCK(curthread->td_proc);
@@ -163,9 +165,9 @@ ia32_get_mcontext(struct thread *td, struct ia32_mcontext *mcp, int flags)
 	mcp->mc_ss = tp->tf_ss;
 	mcp->mc_len = sizeof(*mcp);
 	ia32_get_fpcontext(td, mcp);
-	mcp->mc_fsbase = td->td_pcb->pcb_fsbase;
-	mcp->mc_gsbase = td->td_pcb->pcb_gsbase;
-	td->td_pcb->pcb_full_iret = 1;
+	mcp->mc_fsbase = pcb->pcb_fsbase;
+	mcp->mc_gsbase = pcb->pcb_gsbase;
+	set_pcb_flags(pcb, PCB_FULL_IRET);
 	return (0);
 }
 
@@ -207,7 +209,7 @@ ia32_set_mcontext(struct thread *td, const struct ia32_mcontext *mcp)
 	tp->tf_rflags = rflags;
 	tp->tf_rsp = mcp->mc_esp;
 	tp->tf_ss = mcp->mc_ss;
-	td->td_pcb->pcb_full_iret = 1;
+	set_pcb_flags(td->td_pcb, PCB_FULL_IRET);
 	return (0);
 }
 
@@ -397,7 +399,7 @@ freebsd4_ia32_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
 	regs->tf_ss = _udatasel;
 	regs->tf_ds = _udatasel;
 	regs->tf_es = _udatasel;
-	td->td_pcb->pcb_full_iret = 1;
+	set_pcb_flags(td->td_pcb, PCB_FULL_IRET);
 	/* leave user %fs and %gs untouched */
 	PROC_LOCK(p);
 	mtx_lock(&psp->ps_mtx);
@@ -518,7 +520,7 @@ ia32_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
 	regs->tf_ss = _udatasel;
 	regs->tf_ds = _udatasel;
 	regs->tf_es = _udatasel;
-	td->td_pcb->pcb_full_iret = 1;
+	set_pcb_flags(td->td_pcb, PCB_FULL_IRET);
 	/* XXXKIB leave user %fs and %gs untouched */
 	PROC_LOCK(p);
 	mtx_lock(&psp->ps_mtx);
@@ -613,7 +615,7 @@ freebsd4_freebsd32_sigreturn(td, uap)
 	regs->tf_gs = ucp->uc_mcontext.mc_gs;
 
 	kern_sigprocmask(td, SIG_SETMASK, &ucp->uc_sigmask, NULL, 0);
-	td->td_pcb->pcb_full_iret = 1;
+	set_pcb_flags(td->td_pcb, PCB_FULL_IRET);
 	return (EJUSTRETURN);
 }
 #endif	/* COMPAT_FREEBSD4 */
@@ -702,7 +704,7 @@ freebsd32_sigreturn(td, uap)
 	regs->tf_flags = TF_HASSEGS;
 
 	kern_sigprocmask(td, SIG_SETMASK, &ucp->uc_sigmask, NULL, 0);
-	td->td_pcb->pcb_full_iret = 1;
+	set_pcb_flags(td->td_pcb, PCB_FULL_IRET);
 	return (EJUSTRETURN);
 }
 
@@ -742,8 +744,7 @@ ia32_setregs(struct thread *td, struct image_params *imgp, u_long stack)
 	fpstate_drop(td);
 
 	/* Return via doreti so that we can change to a different %cs */
-	pcb->pcb_flags |= PCB_32BIT;
-	pcb->pcb_flags &= ~PCB_GS32BIT;
-	td->td_pcb->pcb_full_iret = 1;
+	set_pcb_flags(pcb, PCB_32BIT | PCB_FULL_IRET);
+	clear_pcb_flags(pcb, PCB_GS32BIT);
 	td->td_retval[1] = 0;
 }